24V Ready to fire

9

93Chummins

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Dec 31, 2013
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Been working on this truck for over a year and finally ready to light it up, BUT. . . . Sum-Ting Wong. Quick run down: '93 Chevy with '98.5 24V NV4500 so no PCM. I installed a FASS fuel system and plugged it in to the factory ECM harness plug. I used a relay to power the ECM and Injector Pump. I am getting 12V as far as the Injector Pump with the key in run, but I can't get the FASS pump to kick on even when I bump the starter. It is possible the switched wire I'm using is not hot in start. I haven't had help so that I can check it while cranking. Worried ECM is bad too, I did not remove it while welding on motor mounts. If I knew how to check that the grid heater is working I might be able to eliminate that concern. Any ideas from anyone with experience with this kind of thing would be more than welcome and truly appreciated. Thank you.
 

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On my AD I found a hot wire in the RUN position and tapped it there..it needs to be hot while truck is running not just starting..unless it totally just misunderstood you..
 
Yeah, I got power with key in run, but not sure about start. Next step is to have somebody crank it while I check for power. I'm a bit confused. My wiring schematic shows the wire I'm using as both hot in start and run AND hot in ACC and run. So I just have to check it. It's shown as a circuit for the gauges, but if I recall, don't gauges usually blink out while cranking?
 
OK, so the wire I'm using to power my ECM and Injector Pump is hot in start and run, however, I am only getting .29 volts out of the yellow w/white wire that powers the lift/transfer pump. This voltage is making it all the way to the FASS system relay, but not to the pump. I'm guessing .29 volts is not enough to trigger the relay. Does the ECM require any signals before sending the required amount of voltage to power the lift pump, i.e. water in fuel, wait to start? The only sensors I have are the ones on the motor itself.
 
Is that signaled by the Cam Position Sensor? What is the proper way to check sensor function? Leaning toward toggling the lift pump, but if a sensor is bad, motor probably won't run correctly anyway. Again, .29 voltage remains even when turning motor over. Thanks
 
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OK, folks! Just got it fired up for the first time tonight. :cheer: I ended up toggling the lift pump by a switched wire so that works now. Took awhile to bleed fuel system, but finally lit up and settled into a very nice, smooth idle. My next problem is I have the common dead pedal I read about everywhere. I unhooked the connector from the APPS with the truck off/key in run and checked for voltage between the supply and ground wires. I only got .03 volts. I'm getting real close to just pulling the ECM and sending it off to have it looked at, but I'd like to make sure everything else is operating properly. I'm still using the Auto ECM. Most people seemed to think this wouldn't cause any serious issues. It is good to hear it run again after 15 months, and know I'm getting close. Thanks for all the advice.
 
Did a little research and found a thread on cumminsforum by a guy doing a swap into a similar vehicle. Apparently, I need to send switched (hot in run and start) 12v to the light green/black wire at pin 5 at the ECM. I'm also redoing the red w/white wires at pins 48 and 50 at the ECM with fused 12v. The red w/white wire at pin 7 on the Injection Pump will remain on a relay. Hopefully this works.
 
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